This invention relates to composite articles and in particular relates to composite load-bearing covers, such as manhole covers.
Covers for manholes, underground storage tanks such as petrol storage tanks, delivery chutes to cellars or basement warehouses, and the like, have generally been made from iron or steel to provide the necessary load-bearing capacity to support vehicular traffic passing thereover. In order to provide the necessary structural rigidity, the thickness of metal employed must be relatively great and therefore the cost and the weight of such covers is high. Indeed, the cover for a filling station petrol storage tank may well weigh over one hundred pounds. Therefore, removing and replacing such heavy covers is both difficult and hazardous for staff needing to gain access.
The present invention seeks to provide an inexpensive and lightweight composite cover which nevertheless has the structural strength to replace the traditional iron or steel covers.